The shipping industry employs the use of large cargo containers to transport cargo to be shipped from one location to another. These containers can be easily and conveniently loaded and unloaded, and moved from one transport vehicle or vessel to another for transport across land and/or sea. These containers eliminate the historical requirement to manually transfer cargo from vessel to vessel and from vehicle to vehicle during its course of being transported from one place to another.
The cargo containers in use today have become standardized in dimension and structural, and are such that they can be easily, conveniently and securely stacked vertical in a side by side and end to end relationship to maximize the use of hold and deck space on ships and the like, on which such containers are placed. Trailers are standardized to carry the containers for delivery by trucks and the like.
The principal shortcoming found in the use of cargo containers of the character referred to above resides in the fact that day to day commerce can require that these containers be transported empty from a station or site of delivery of cargo to a next site or station for receipt or loading of cargo. Such transporting of empty containers is non-profitable since each such container occupies valuable and costly space on the ship that could otherwise accommodate a loaded or filled container. Further, the handling and shipping of both loaded and empty containers creates a multitude of other problems. One such problem resides in arranging light, empty containers and heavy, loaded containers aboard ships in such a manner that the ships are properly and safely trimmed.
When transporting a high percentage of empty containers, the voyage of such ships is uneconomical and must be made up somewhere along the way with increased costs of goods and shipping. Accordingly, large economic savings in shipping by containers could be realized if empty containers could be folded or collapsed so that they occupy a fraction of the space they occupy when in their expanded configuration. For example, if two containers when collapsed could occupy the space of one container in its normal configuration, the cost of shipping empty collapsed containers would be roughly reduced about one-half.
The prior art has proposed a number of nesting cargo container structures intended to effectively reduce the space required for their shipment when they are empty. While certain proposed nesting containers might well serve such an end, it is understood that they are seriously wanting in certain material respects. For example, a shortcoming found in space saving cargo containers proposed by the prior art includes the deconstruction of the container with the resultant burden of removable or separable parts which are subject to being misplaced, lost, damaged and/or stolen. Experience has taught that if parts of equipment such as cargo containers can be removed and lost or readily damaged, such parts will be removed, lost and/or damaged in the normal course of their use and that great difficulties and inconveniences will be experienced in maintaining such containers.
The construction of traditional cargo containers are made to comply with ISO standard 1496-1, which specifies dimensional and strength requirements but not construction methods. Cranes provided assistance for handling some loads and the advent of the fork lift truck led to the introduction of palletized loads which avoided handling of individual items when transferring between different types of transport at freight terminals. Palletized loads still offered limitations in relation to the speed of handling and especially in relation to their stacking capacity. This has led to development and widespread adoption of containers.
Various sizes have now become standardized 20′ (6 m) long containers are the most common. The width has become standardized at 2438 mm. Containers can be loaded at the source and are easily transferred between different types of transport e.g. road, rail or ship. Forklift trucks can be used to load a container with palletized loads. Pallets are approximately 48″×40″ (1200-1000 mm) square. Ten pallet places can be accommodated in a standard container. Large ocean going vessels have been designed for handling the containers which can be stacked one on top of the other perhaps as many as seven high. Containers have the advantage of offering protection to the contents within. There is a constant flow of containers around the globe to meet the requirements for the supply of raw materials and products. To maximize container utilization it is desirable to be able to fill a container whenever it is moved from one location to another, but it has been calculated that 20% of containers are transported empty on re-positioning runs.
Typical “40-foot” container construction consists of 8 industry-standard corner fittings arranged in space at the corners of a generally 8′ wide by 8′6″ high by 40′ long rectangular box. Various tubes and channels formed from steel sheet are welded between the corner fittings. Steel sheets are welded between these tubes and channels, forming the roof, side walls and front wall. These sheets are typically corrugated to impart sufficient rigidity to the sheet to allow the walls to be made from a single sheet of steel. Door leaves are installed in place of a rear wall and allow cargo to be loaded and unloaded, while the floor is typically made from wood mounted atop a welded grid of steel channels. FIG. 1 shows the construction of the side wall of a typical container. The corner fittings (1) are located at the corners of each wall. A portion of the wall has been removed to reveal the corrugation of the steel sheet (2), which is welded to front corner post (3), rear corner post (4), upper rail (5), and lower rail (6). This method of construction also generally applies to the opposite side wall, the front wall and also to the roof. The door leaves are typically constructed similarly, less corner fittings.
The result of this method of construction is that the interior and exterior faces of the walls are not flat and smooth. The heavy corrugations of the interior walls often make loading and unloading of cargo difficult as the forks and tires of the forklift get hung up on the corrugations while maneuvering. This is particularly troublesome where loads are balanced on pallets and the uneven surfaces can also cause spilling of the loads, sometimes requiring special lifting equipment to restack the pallets. There is a need in the art for a container that has more even surfaces that resist interference with forklift tires, forks, and the like.
Yet another shortcoming found in collapsible containers proposed by the prior art is the lack of structural features which enable or facilitate the folding down and setting up or opening of such containers in a simple and effective manner.